XmlPad problems with XPath for finding duplicate nodes - duplicates

Question

[EDIT] It seems that there is a bug in the XML Editor I'm using (XmlPad) that prevents the Xpath query from returning the correct results. I've tested the same query using two online tools (http://www.zrinity.com/xml/xpath/xpath.cfm and http://www.futurelab.ch/xmlkurs/xpath.en.html) and it seems to work. biziclop also commented that the query works correctly in Oxygen.
I've got this structure:
<?xml version="1.0" encoding="utf-8"?>
<root>
<itemlist>
<item>
<code>0001.0.00</code>
<category>709</category>
</item>
<item>
<code>0001.0.00</code>
<category>709</category>
</item>
<item>
<code>0002.0.00</code>
<category>708</category>
</item>
</itemlist>
<itemlist>
<item>
<code>0016.0.00</code>
<category>52</category>
</item>
<item>
<code>0016.0.00</code>
<category>52</category>
</item>
<item>
<code>0016.0.00</code>
<category>51</category>
</item>
<item>
<code>0016.0.00</code>
<category>50</category>
</item>
<item>
<code>0869.0.00</code>
<category>52</category>
</item>
<item>
<code>0869.0.00</code>
<category>51</category>
</item>
<item>
<code>0869.0.00</code>
<category>50</category>
</item>
</itemlist>
</root>
I want find all items where the previous item has the same category.
This Xpath query:
//item[category = preceding-sibling::item[1]/category]
returns the following nodes:
<item>
<code>0001.0.00</code>
<category>709</category>
</item>
<item>
<code>0016.0.00</code>
<category>52</category>
</item>
<item>
<code>0869.0.00</code>
<category>52</category>
</item>
The last item node in the result set is incorrect, because the value of the previous item's category in the input is not 52 so it should not be returned.
Is there an Xpath query that will return the results I want?

Answer 1

This XPath is absolutely correct. I've tested it with Saxon XSLT processor as follows:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/">
<xsl:copy-of select="//item[category
= preceding-sibling::item[1]/category]"/>
</xsl:template>
</xsl:stylesheet>
With results:
<item>
<code>0001.0.00</code>
<category>709</category>
</item>
<item>
<code>0016.0.00</code>
<category>52</category>
</item>
You might want also try alternatives:
//item[category = ./preceding-sibling::item[1]/category]
/root/itemlist/item[category = ./preceding-sibling::item[1]/category]